Effects of Including Sprints in LIT Sessions during a 14-d Camp on Muscle Biology and Performance Measures in Elite Cyclists

A training goal-oriented categorization model of high-intensity interval training

There are various categorization models of high-intensity interval training (HIIT) in the literature that need to be more consistent in definition, terminology, and concept completeness. In this review, we present a training goal-oriented categorization model of HIIT, aiming to find the best possible consensus among the various defined types of HIIT. This categorization concludes with six different types of HIIT derived from the literature, based on the interaction of interval duration, interval intensity and interval:recovery ratio. We discuss the science behind the defined types of HIIT and shed light on the possible effects of the various types of HIIT on aerobic, anaerobic, and neuromuscular systems and possible transfer effects into competition performance. We highlight various research gaps, discrepancies in findings and not yet proved know-how based on a lack of randomized controlled training studies, especially in well-trained to elite athlete cohorts. Our HIIT "toolbox" approach is designed to guide goal-oriented training. It is intended to lay the groundwork for future systematic reviews and serves as foundation for meta-analyses.

Low- and high-volume blood-flow restriction treadmill walking both improve maximal aerobic capacity independently of blood volume

AIM

Assess the effect of low- and high-volume blood flow restriction training (BFR) on maximal aerobic capacity (VO2 max) and determine if alteration in VO2 max is mediated through changes in hemoglobin mass (Hbmass) and blood volume.

METHODS

Participants' Hbmass (CO-rebreathe), single, and double-leg VO2 max and blood volume regulating hormonal responses (renin and copeptin) were measured before and after BFR training. Training consisted of treadmill walking either (1) twice-daily for 4week (CON and BFRHV ) or (2) twice-weekly for 6week (BFRLV ). Each session consisted of five intervals (3 min, 5% incline, 5 km/h, 100% of lowest occlusion pressure), with 1 min of standing rest between sets.

RESULTS

VO2 max increased using both training exposures, in as quickly as 2-weeks (BFRLV baseline to 4week: +315 ± 241 mL (8.7%), p = 0.02; BFRHV baseline to 2week: +360 ± 261 mL (7.9%), p < 0.01), for the BFRLV and BFRHV groups, with no change in CON. Single- and double-leg VO2 max improved proportionately (single/double-leg VO2 max ratio: BFRLV 78 ± 4.9-78 ± 5.8%, BFRHV 79 ± 6.5-77 ± 6.5%), suggesting that the mechanism for increased VO2 max is not solely limited to central or peripheral adaptations. Hbmass remained unchanged across groups (CON: +10.2 ± 34 g, BFRLV : +6.6 ± 42 g, BFRHV : +3.2 ± 44 g; p = 0.9), despite a significant release of blood volume regulating hormones after initial BFR exposure (renin +20.8 ± 21.9 ng/L, p < 0.01; copeptin +22.0 ± 23.8 pmol/L, p < 0.01), which was blunted following BFRHV training (renin: +13.4 ± 12.4 ng/L, p = 0.09; copeptin: +1.9 ± 1.7 pmol/L, p = 0.98).

CONCLUSION

BFR treadmill walking increases VO2 max irrespective of changes in Hbmass or blood volume despite a large release of blood volume regulating hormones in response to BFR treadmill walking.

A Perspective on High-Intensity Interval Training for Performance and Health

Interval training is a simple concept that refers to repeated bouts of relatively hard work interspersed with recovery periods of easier work or rest. The method has been used by high-level athletes for over a century to improve performance in endurance-type sports and events such as middle- and long-distance running. The concept of interval training to improve health, including in a rehabilitative context or when practiced by individuals who are relatively inactive or deconditioned, has also been advanced for decades. An important issue that affects the interpretation and application of interval training is the lack of standardized terminology. This particularly relates to the classification of intensity. There is no common definition of the term "high-intensity interval training" (HIIT) despite its widespread use. We contend that in a performance context, HIIT can be characterized as intermittent exercise bouts performed above the heavy-intensity domain. This categorization of HIIT is primarily encompassed by the severe-intensity domain. It is demarcated by indicators that principally include the critical power or critical speed, or other indices, including the second lactate threshold, maximal lactate steady state, or lactate turnpoint. In a health context, we contend that HIIT can be characterized as intermittent exercise bouts performed above moderate intensity. This categorization of HIIT is primarily encompassed by the classification of vigorous intensity. It is demarcated by various indicators related to perceived exertion, oxygen uptake, or heart rate as defined in authoritative public health and exercise prescription guidelines. A particularly intense variant of HIIT commonly termed "sprint interval training" can be distinguished as repeated bouts performed with near-maximal to "all out" effort. This characterization coincides with the highest intensity classification identified in training zone models or exercise prescription guidelines, including the extreme-intensity domain, anaerobic speed reserve, or near-maximal to maximal intensity classification. HIIT is considered an essential training component for the enhancement of athletic performance, but the optimal intensity distribution and specific HIIT prescription for endurance athletes is unclear. HIIT is also a viable method to improve cardiorespiratory fitness and other health-related indices in people who are insufficiently active, including those with cardiometabolic diseases. Research is needed to clarify responses to different HIIT strategies using robust study designs that employ best practices. We offer a perspective on the topic of HIIT for performance and health, including a conceptual framework that builds on the work of others and outlines how the method can be defined and operationalized within each context.

Development of Cycling Performance Variables and Durability in Female and Male National Team Cyclists: From Junior to Senior

AIM

This study investigated the development of power profiles and performance-related measures from the junior level (<19 yr) via U23 (19-23 yr) to senior level (>23 yr) in 19 female and 100 male Norwegian national team cyclists.

METHODS

A total of 285 tests were performed in a 3-d laboratory-standardized testing regime. The tests included power profiles with shorter duration (6-60 s) and longer durations (12-30 min) together with performance-related measures: critical power (CP), work capacity above CP (W'), power output at 4 and 2 mmol·L -1 [BLa - ] (L 4 and L 2 ), maximal aerobic power (W max ), and maximal oxygen uptake (V̇O 2max ), gross efficiency (GE), and pedaling efficiency.

RESULTS

Females and males evolve similarly when maturing from junior via U23 to senior categories (all P > 0.07), except for V̇O 2max , which increased in females (but not males) from junior to senior level (534 ± 436 mL·min -1 , P = 0.013). In general, only performances of longer durations improved with age (12 and 30 min, P = 0.028 and P = 0.042, respectively). Performance-related measures like W max , V̇O 2max , CP, L 4 , L 2 , and pedaling efficiency in the fresh state improved with age (all P ≤ 0.025). Importantly, performance in the semifatigued state during a 5-min maximal test was also improved with age ( P = 0.045) despite a higher external energy expenditure before the test ( P = 0.026).

CONCLUSIONS

Junior cyclists show highly developed sprint abilities, and the primary improvements of absolute power outputs and performance-related measures are seen for durations >60 s when maturing to U23 and senior categories. However, the durability, i.e., the capacity to maintain performance in a semifatigued state, is improved with age.

Performance-Related Physiological and Haematological Changes During Pregnancy and Postpartum in a Well-Trained Cyclist Performing Endurance Training

Purpose: To describe the performance-related physiological and haematological changes in a well-trained cyclist (peak oxygen uptake, VO2peak: 54.9 ml min-1·kg-1) performing endurance training during pregnancy and postpartum. Methods: Training data was systemized by training form (endurance and resistance), intensity (low- (LIT), moderate-, and high-intensity training), and modality (cycling, running, hiking, XC-skiing, strength training and other). Power output at 4 mmol L-1 [BLa-] (L4), maximal aerobic power (Wmax), and VO2peak as well as haemoglobin mass, blood volume, plasma volume and red blood cell volume (RBCV) were measured at different time points during pregnancy and 12 weeks postpartum. Results: L4 and Wmax increased by 3% while absolute VO2peak was unaltered from gestational wk 2 to 14, despite 12 and 14% increases in RBCV and BV. After delivery, BV was reduced by 7% but RBCV was maintained 5% above start-pregnancy levels, while VO2peak almost returned to (-1%), and Wmax increased by 5% above start-pregnancy levels 12 weeks postpartum. Conclusion: This case-study illustrates a disassociation between increases in haematological values and VO2peak during pregnancy. Furthermore, a quick resumption of LIT and a gradually increasing intensity of training in the 12 weeks following delivery ensured a return to start-pregnancy levels of VO2peak and corresponding improvements in Wmax. Although general recommendations cannot be given on the basis of these data, this study provides a framework for investigating pregnant endurance athletes and contributes to the generation of new hypotheses in this field.